Figure 2 shows the year-over-year change in the methane concentration of the atmosphere, and indicates not only that the growth rate of methane has been declining, but also that on several occasions during the past decade or so, it has dropped to very near zero (or even below) indicating that no increase in the atmospheric methane concentration (or a even a slight decline) occurred from one year to the next.

This behavior is quite perplexing. And while we are not sure what processes are behind it, we do know one thing for certain--the slow growth of methane concentrations is an extremely cold bucket of water dumped on the overheated claims that global warming is leading to a thawing of the Arctic permafrost and the release of untold mega-quantities of methane (which, of course, will lead to more warming, more thawing, more methane, etc., and, of course, to runaway catastrophe).

The hypothesis is used to good effect by SF author John Barnes in his excellent (Hugo & Nebula nominee) book, Mother of Storms. Barnes is one of those "good science" SF authors, who also is a fairly good writer. There's a strong sexual component in this one (i.e., it's not for pre-teens or even early teens) but it's an excellent read.